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Otitis Externa

Otitis Externa

What causes ear disease?

Ear disease usually results in the over-production of wax, which occurs in response to irritation. Allergic skin disease affecting the ears is the most common cause, especially in recurring cases; other causes of ear infections include ear mites; foreign bodies such as grass awns or foxtails; or hair growth deep in the canal. Anatomic changes to the ear canal such as scar tissue from previous ear infections can also contribute to recurrence. The moisture of the wax promotes bacterial growth and infection.


How do I know if my pet’s ears are bothering him/her?

Many pets with ear disease will be seen scratching at their ears, shaking their head or holding one ear slightly dropped. Your pet may resent having their ears touched or seem painful in this area. Discharge and odor may be noticeable as well.


Why is this a problem?

Aside from being uncomfortable, ear infections can cause other problems. When a dog or cat with uncomfortable ears shakes and scratches vigorously, a blood vessel in the earflap may rupture. This leads to bleeding into the tissues of the pinna, a condition known as an aural hematoma. The usual recommendation is to have the blood clots removed and to bandage and clean the ear under anesthesia. In addition, chronic ear infections can cause scarring of the ear canal, making it difficult to clean ears and administer medication, and making it more likely to develop. Rarely, infections can reach the middle ear, and affected animals may have a head tilt, a lack of balance, and unusual back-and-forth eye movements called nystagmus. These symptoms are called vestibular signs and represent a complication of middle ear infection. Middle ear infections can also cause paralysis of the facial nerve, leading to a slack-jawed appearance on that side of the face.


How are ear infections diagnosed?

A sample of ear discharge is commonly examined under the microscope to look for any infectious organisms (bacteria or yeast) and to assist in selecting medications for home use. An otic exam may also be performed with an otoscope to take a closer look at your pet’s ear canal and tympanic membrane (ear drum).


How are ear infections treated?

Most ear infections are cleared up simply with cleaning followed by medication at home. If there is only mild debris in the ear canals, simple disinfection and washing of the ear is adequate. After a couple of weeks of home treatment, the ear canals are rechecked to be sure the infection is gone. In most cases this completes treatment but for stubborn cases, we must proceed to the next step.


What if this is not effective?

Some pets have chronic ear problems in which the infection is not controlled by medications or returns when the medications have been discontinued. In these cases, the ear discharge should be cultured so that the precise organism can be pinpointed and treated specifically. Regular treatment at home with disinfecting ear washes should become part of the pet’s grooming routine. Further testing may be needed in order to determine why the infection continues to recur. Chronic ear infections typically have an underlying cause (usually allergy). It is important to address this problem in addition to the infection itself so as to minimize on-going ear inflammation.


Some ear infections simply cannot be controlled with the above steps. These cases have transcended medical management and must proceed to surgical management, though this is considered a last resort. Ear infections can be especially frustrating as they have the ability to draw out for months, even years, even with the best of treatment. It is important to have a logical approach, to know what sort of infection is in the ear, to do proper home care regularly, and to have regular recheck appointments. If a patient has a history of particularly stubborn ear infections or numerous recurrences, treatment focus shifts to prevention once the acute infection is eliminated. 

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